Conventional direct acting staplers are well known for fastening papers and other tasks. The handle is linked directly to the striker so that, above the striker, the handle moves the same as or similarly to the striker. Such staplers are sometimes known as a direct action stapler. For example, in a direct action stapler, a striker commonly moves about ½ inch to eject and install a common 26/6 type or similar staple. In this example, the handle near the striker moves toward the body about the same ½ inch as it is pressed through its complete stroke. Such staples can be used to fasten more than 20 sheets of 20 lb. type paper. But they are commonly used for fewer sheets, five or less for example.
Such conventional staplers are known to require high pressing forces to operate. Part of the effort is to separate a front staple from the rack of staples held inside the stapler. In this process, the glue that holds the staple stick or rack together must be sheared to free the front staple. When the glue is weak this effort is not excessive. But when the glue is strong, shearing the glue is often the largest factor in pressing effort, particularly in low sheet counts. The variation in glue accounts for much of the unpredictability in conventional stapling. In some cases, glue shearing can require 15 lbs. of force just to allow the handle to start moving. A well-known way to generate sufficient force to overcome this problem is to bang the handle with a clenched fist.
To reduce any need to bang the hand with the fist and to ease the stapling process, the handle may be less directly linked to the striker to allow reduced effort operation. For example, the handle may operate to energize a power spring. At a pre-release position of the handle the spring suddenly ejects and installs a staple. In this manner, the force peaks through the fastening operation are reduced. The impulse or shock overcomes the glue shear force among others. Further, the handle may move more than the striker for enhanced leverage.
Another option to reduce stapling effort employs extra leverage. For example, a handle may extend well past a front of the stapler body to provide a simple, longer lever to add handle travel to the action. The base of such a stapler must correspondingly extend forward to the front end of the handle to provide a reaction location for the very forward force application. A further mechanism allows a shorter device by linking a base to the handle through a multi-link system. This link effectively compresses the body between the handle and the base to hold the body against the base. In this design, pressing the handle toward the body causes the base to move up toward the body even if the base is not being touched. This is one way to observe such conventional leveraged action. The first leverage option is a long device that is not convenient on a desktop. The second device requires a complex mechanism.
In both examples the base is integral to the function of enhanced leverage. Therefore, neither of these devices allows for use as a tacker with the base opened. The long handled stapler would tip forward without its long base. The handle-to-base linked version has the body rising away from the work surface as the staple exits if there is no base under the staple. This is because the force by the staple on the work surface is leveraged by design to be more than a force upon the handle above the striker. For example, a 10 lb. handle force may by leveraged to become a 20 lb. staple exit force. This net imbalance moves the body away from the work surface toward the handle with a force of 10 lbs. If the base is linked to the body as in common leveraged staplers then the body cannot move away from the base. But as discussed above, the base must then be the working surface. In contrast, a conventional non-leveraged stapler has the force by the staple being substantially the same as the force acting on the handle; there is no net vertical force on the body.
The handle-to-base link requirement has not been apparently addressed by non-spring actuated staplers. In a spring actuated stapler, the body does not move away from any working surface even as the handle can be leveraged to the striker through the spring. This is because the fastening operation occurs instantly; the momentum from the mass of the body holds the body in its operative position during this instant action.